Magnetic testing device for detecting loss of metallic area and internal and external defects in elongated objects
US4096437A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1976 |
| Grant date | Jun 20, 1978 |
| Priority date | — |
| Expiry date | Sep 30, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/82
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A magnetic testing device for detecting defects in elongated objects is disclosed. The testing device comprises a permanent magnet assembly having poles adapted to be spaced apart in the longitudinal direction of an elongated object for inducing a longitudinal magnetic flux in a section of the object between the poles of the magnet assembly which is strong enough to saturate such section of the object, a tubular pole piece substantially centered on the elongated object adjacent each pole of the permanent magnet assembly for directing the magnetic flux radially into the object at one pole and out of the object at the other pole, Hall effect devices spaced around at least one pole piece in the path of the magnetic flux for sensing the radial flux entering into the elongated object, and means for sensing the variations of such magnetic flux as an indication of loss of metallic area in the object. The magnetic testing device is also provided with a leakage flux sensor located between the pole pieces for detecting external and internal defects in the object.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.